1. Field of the Invention
The present invention relates to a folding preparation body of a driver seat airbag which can be mounted compactly in a steering wheel of a vehicle, and a folding method of a folded body.
2. Description of the Related Art
In the related art, a steering wheel in which such a driver seat airbag is mounted includes a ring portion which is gripped when steering, a boss portion which is disposed near the center of the ring portion, and a spoke portion which connects the boss portion and the ring portion while a gap is provided on the front side of the boss portion when steering straight ahead. A folded body obtained by folding an airbag is mounted in the boss portion of the steering wheel (for example, see JP-A-2007-261565). In the airbag, an outer circumferential wall includes a vehicle body side wall having an inflow opening through which an inflation gas is allowed to flow disposed near the center thereof, and a driver side wall which is disposed to face the vehicle body side wall by connecting an outer circumferential edge to the outer circumferential edge of the vehicle body side wall. In order to be compact, the folded body of the airbag is formed in such a folded shape that the outer circumferential edge of an initial preparation body in a state where the driver side wall and the vehicle body side wall in the outer circumferential wall of the airbag are overlapped is gathered to the upper side of the inflow opening.
The outer circumferential edge of the initial preparation body in a state where the driver side wall and the vehicle body side wall in the outer circumferential wall of the airbag are overlapped is folded using a plurality of radial paddles and the like to be gathered to the upper side of the inflow opening, and a folded portion obtained by roll-bending and folding toward the vehicle body side wall is provided on the front edge side, thereby forming the folded body (for example, see US 2005/0269807). In the folded body having such a configuration, although a driver is too close to the boss portion at the time of inflation after the steering wheel is mounted in the boss portion, a portion of the folded portion on the front edge side enters the front portion of the boss portion between the boss portion and the ring portion to be inflated on the lower surface side of the ring portion, and thus the pressing force to the close driver can be reduced.
However, in the conventional folded body of the driver seat airbag, the rolled folded portion is provided on the front edge side as disclosed in US 2005/0269807 corresponding to the close driver, and the rolled folded portion has rigidity so that it is hardly bent. Further, although a technology of approaching the inflow opening in JP-A-2007-261565 is applied to fold the folded body compactly, the rigidity of the rolled folded portion inhibits the folded body from being folded compactly.